A Time-Series Novelty Detection Chip for Sonar

T.K. Horiuchi and R. Etienne-Cummings

Keywords

Sonar, change detection, low-power

Abstract

A time-series processor chip, intended for sonar mapping and novelty
detection applications, has been designed, fabricated, and tested.
The chip, when coupled with an external sonar bearing estimation
unit, receives an image of the sonar environment as a voltage
waveform. The bearing of an object is given to the chip by
the magnitude of the voltage, and its range is given by the time
following the transmission of the sonar “ping". The chip stores this
voltage waveform in a bank of sample-and-hold (S/H) elements and
compares it to a previously stored trace. Objects (echo returns)
that move in either azimuth or range are immediately detected and
reported. The chip contains 54 S/H and detector elements that
are sequentially triggered by an on-board clock. Operating in the
CMOS subthreshold region of operation, the novelty detection chip
is designed for ultra-low power and miniature smart surveillance
systems. Implemented in a CMOS 0.5 µm process, it consumes
less than 20 µW@ 8 Hz repetition rate (and less than 6 µW in a
fully quiescent mode) with a 3 V supply, and occupies less than
0.3 sq. mm.